1. Technical Field
The present invention relates to mobile communications and, more particularly, to signaling during a handover.
2. Discussion of Related Art
Although the invention arose in the context of the downlink packet data transmission in UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access, it is not limited thereto and the explanations that follow should be understood in a way that does not limit the invention to that context. High Speed Downlink Packet Access (HSDPA) is a feature included in Release'5 3GPP specifications and is further enhanced in Release 6 with the support of fractional Dedicated Physical Channel (DPCH), called F-DPCH, and the support of Signalling Radio Bearer mapping on the High Speed Downlink Shared Channel.
The invention addresses but is not limited to the Release 7 HSDPA improvement under discussions, which aims to speed up the handover and serving HS-DSCH cell change processes with HSDPA especially with real time applications, such as VoIP (Voice over Internet Protocol). One of the proposals has been presented in R1-050324 (Lucent) 3GPP TSG-RAN1 meeting # 40bis, 4-8 Apr. 2005, Beijing, China, 2005.
As expressed in R1-050324, the UTRAN pre-configures the BTS (Base Transceiver Station or “Node B” for a UE initiated cell change. After the UE has sent the layer 1, layer 2 or layer 3 indication e.g. RRC (Radio Resource control) layer measurement report indicating the cell change, the UE starts listening to the target cell. The UE can listen to both the source and target cells simultaneously (R1-050324).
The present invention addresses but is not limited to the L3 signaling scheme for the HS-DSCH serving cell change solutions where the UE changes the HS-DSCH reception to the other “pre-configured” cell after indicating the cell change in L1/2/3 signaling to the UTRAN. The prior art solution (R1-050324) does not solve the problem of how the UTRAN (RNC) is made aware (especially when Bi-casting is utilized by the UTRAN in the source and target cells) that the change is successful or give possibilities for UTRAN conform the cell change or further reconfigure the existing pre-configured configuration. In addition, the proposed scheme requires protocol interaction to keep RRC in correct state.